The goal of this project is to apply biomarkers of exposures and outcomes that have been developed thus far in the UC Davis Superfund laboratories to human populations with likely exposures to hazardous substances so as to provide laboratory/biologic assessment of exposures and health outcomes. This project is timely at this stage of the UC Davis Superfund effort in taking assay techniques that have been developed here into a real-lifer human setting to provide both practical information about the feasibility of such approaches as well as objective data about the likelihood of exposure of human populations to toxicants of interest to Superfund and the relation of such exposures ti adverse health effects in humans. Specifically the aims of this project are: a) evaluate the adverse human health effects, particularly neurologic and neurobehavioral effects, or organophosphate (OP) exposure in children in a farmworker community using monthly urine samples from mothers (including farmworkers and non-farmworkers) and their children to assess (OP) metabolites, such as glucuronides of Ops; b) to determine the prevalence of exposure and compare immunoassay to gas chromatography results; c) to evaluate the likely routes of exposure; d) to evaluate the relation of potential exposure to environmental endocrine disruptors and other potentially hazardous exposures to adverse reproductive and other human health effects in a residential community adjacent to a local Superfund site; and e) to compare thyroid hormone levels in opportunistic blood samples and treatment for thyroid disorders of household members who are likely and those who are unlikely to be exposed. This project will also provide epidemiologic field studies to examine the role of exposure to hazardous environmental substances in increasing the risk of adverse human health effects.